Refining of vegetal oils and fats



Patented Sept. 26, 1933 UNITED STATES PATENT OFFICE 1,927,850 'REFINING F VEGETALOILS AND FATS Max Schellmann, Oppau, and Hans Franzen,

Mannheim, Germany, assignors to I.

G. Farbenindustrie Aktiengesellschaft, Frankfort-onthe-Main, Germany No Drawing. Application December 29, 1931, Serial No. 583,790, and in Germany January 8 Claims.

The present invention relates to the refining of vegetal oils and fats.

It has already been proposed to treat vegetal, i. e. vegetable and animal oils and fats with small quantities of water or with aqueous solucases. Especially in the case of cotton seed oils which have been treated with aqueous solutions of salts or acids and subjected to a distillation for the purpose of deacidification it is impossible to render the colour of the oil lighter by subsequent refining with alkalies.

We have now found that crude vegetal oils and fats, especially cotton oil can be freed from mucilaginous substances in a manner which is readily carried out industrially by heating them with a small quantity of anhydrous boric acid. The quantity of boric acid is generally between about 0.5 and about 5 per cent by weight of the oils and fats, and usually about 1 per cent. The treatment may be carried out for example at atmospheric pressure or with the employment of a vacuum such as from about 20 to about 200 millimetres of mercury, preferably from 25 to millimetres of mercury and is preferably effected by adding the solid boric acid to the oil before or during the heating thereof, the oil being simultaneously thoroughly stirred. Generally speaking, temperatures of about 100 C. and more such as 120, 130 or 150 C. and up to 200 and even about 280 C. are suitable depending on the nature of the oil to be treated, the higher temperatures being usually employed in conjunction with evacuation in which the temperature may be gradually raised up to 280 C. By the treatment according to the present invention, a complete precipitation of the mucilages, resins and the like from the oil is effected. The mucilaginous substances separate in a solid granular form and may be removed by physical or mechanical methods, such as sedimentation or filtration, or any other suitable method before the further treatment, such as subsequent refining with alkali or bleaching earths and, if desired, a final deodorizing with superheated steam. They may also be allowed to remain in the oil and removed during a subsequent refining with alkalies such as a from 5 to 35 per cent aqueous caustic sodaisolution or at any other stage of the further treatment. Clear pale oils or fats are obtained in the said manner from the most variegated vegetal oils and fats such as cotton seed, soya bean, peanut, 60

sesamum, rape seed, sunflower, linseed, poppy seed, olive, coconut, palm, palm kernel, maize,

castor and like vegetable oils as well as tallow, bone fat, and trains and train oils, such as whale and seal train and train oils.

In many cases it is preferable to combine the removal of the mucilaginous substances with the deacidification of the oils or fats, whereby a separation of the fatty acids by distillation as for example according to the U. S. Patent No.

1,622,126 and one of the present inventors U. S. application Ser. No. 334,183, filed January 22, 1929, may be carried out. In this case the oil or fat may be subjected to a treatment in vacuo while leading in an inert gaseous carrier, i. e. '55

gases or vapours such as nitrogen, hydrogen, carbon dioxide or sulphur dioxide mixed with finely divided inert liquids or a finely divided inert liquid alone, such as water, hydrogen peroxide solutions, methyl, ethyl or butyl alcohols,

benzine hydrocarbons, hydrocarbons of the benzene series such as benzene, toluene or xylene, and ethylene glycol-or glycerol, is introduced into the heated oil or fat by means of a nozzle.

In any case the boiling point of the liquid chosen should be below the temperature of working in order to obtain a sudden evaporation and formation of mists from the liquid. In this case, the suitable amount of boric acid (up to about 5 per cent) is added to the oil from the start or is added during the course of the distillation. The dark coloured oils are rendered light in colour by a subsequent refining with alkalies. I

The following examples will further illustrate how this invention may be carried out in practice but the invention is not restricted to these examples.

Example 1 Crude cottonseed oil having an acid value of 6.1 is stirred for half an hour at 130 C. and about 20 millimetres of mercury with 1 per cent by weight of the oil of anhydrous boricacid. The mucilaginous substances which separate are deposited within a short period of time. the subsequent refining with a quantity of a 30 per cent aqueous caustic soda solution corresponding to the acid value of the oil plus 10 per cent of this quantity" a clear pale yellow oil having an acid valuc of 0.1 is obtained. The 110 After loss of neutral oil during refining is only 170 per cent (calculated on the soapstock) contrasted with a normal/loss of about 300 per cent of the soapstock, the quantity of oil absorbed by the crude soap increasing with the content of mucilaginous matter in the original oil employed for saponification.

Example 2 1.5 per cent of anhydrous boric acid is added to crude cotton seed oil having an acid value of Peanut oil having an acid value of 15.3 is subjected to a refining by the process according to the'example of the aforesaid application Ser. No.

334,183 after adding to the oil 1 per cent its weight of anhydrous boric acid. The resulting peanut oil having an acid value of 1.0 is much lighter in colour and is free from mucilaginous substances. The subsequent refining with caus tic soda solution yields a water-white oil having an acid value of 0.1.

Example 4 Crude whale oil having an acid value of 2.8 is intimately stirred with 1.5 per cent of its weight of anhydrous boric acid at about 760 millimetres of mercury and 120 C. for hour. After settling and filtering off, or centrifuging, the mucilaginous matter separated out, a clear pure oil is obtained which can be hardened by hydrogenation in the presence of a nickel catalyst without any difliculty in contrast to the crude oil. If an oil having an acid value above 3 is to be purified, it should be deacidified as far as possible by a treatment with aqueous alkali before heat- .ing it with boric acid.

Example 5 boric acid.

2. In refining crude fatty oils and fats containing mucilaginous matter, the step which comprises heating the said oils and fats at from about to about 280 C. with from about 0.5 to about 5 per cent of their weight of anhydrous boric acid at a pressure below atmospheric pressure.

3. In refining crude fatty oils and fats containing mucilaginous matter, the step which comprises heating the said oils and fats at from about 100 to about 280 C. with from about 0.5 to about 5 per cent of their weight of anhydrous boric acid at a pressure below atmospheric pressure while passing through a current of a finely divided inert liquid, having a boiling point below the temperature employed.

4. In refining crude fatty oils and fats containing mucilaginous matter, the step which comprises heating the said oils and fats at from about 100 to about 280 C. with from about 0.5 to about 5 per cent of their weight of anhydrous boric acid while passing through a current of a finely divided inert liquid, having a boiling point below the temperature employed, and an inert gaseous carrier for that liquid.

5. In refining crude cotton seed oil, the step which comprises heating the said oil to from 100 to 200 C. with from about 0.5 to about 5 per cent of its .weight of anhydrous boric acid.

6. In refining crude cotton seed oil, the step which comprises heating the said oil at about 130 C. with from about 0.5 to about 5 per cent of its weight of anhydrous boric acid.

'7. In refining crude cotton seed oil, the step which comprises heating the said oil at a pressure below atmospheric pressure and at from 100 to 280 C. with from about 0.5 to about 5 per cent of its weight of anhydrous boric acid while passing through a current of a finely divided inert liquid, having a boiling point below the temperature employed.

8. In refining crude cotton seed oil, the step 126 which comprises heating the said oil at a pressure below atmospheric pressure and at from 130 to 280 C. with from about 0.5 to about 5 per cent of its weight of anhydrous boric acid while passing through a current of a mixture of steam and finely divided water.

MAX SCHELLMANN. HANS FRANZEN. 

